Google Calendar vs Nager.Date

The Google Calendar API reads and writes events, calendars, free/busy data, and reminders for any Google account that's granted OAuth consent, with push-notification channels available so an app can watch a calendar for changes instead of polling it. It's the same REST API that powers Calendar add-ons and third-party scheduling tools like Calendly. Usage is free under Google's shared per-minute and per-project quotas (10,000 requests/minute/project as of the May 2026 quota update); there's no separate paid tier for the API itself, only future overage billing above a 1,000,000-requests-a-day threshold.

Nager.Date is a free, open-source public holiday API covering more than 100 countries, with endpoints for a year's full holiday list, the next public holiday, whether today is a holiday, and country/county metadata — all keyless JSON with no rate limiting. It's maintained on GitHub by a single developer and is popular as the default holiday backend baked into several scheduling and HR libraries specifically because it needs no signup.